From the prior art, different positioning devices of the generic type have become known, which are used in a variety of technical fields. The known positioning devices serve to hold an object in position. Such positioning devices are therefore used, for instance, to position a workpiece relative to a tool such that the workpiece can be worked with the aid of the tool. In the automobile industry, a body part of a vehicle, for instance, is positioned in a work station or similar with the aid of usually a plurality of positioning devices. The thus positioned vehicle body can then be machined by, for example, welding robots.
Thus, U.S. Pat. No. 5,787,758 describes a three-axis positioning device which serves for the positioning of objects such as, for instance, workpieces, tools, sensors, optical surfaces, and so on. The known positioning device has a supporting structure, which is connected by positioning elements to an adjustable machine component. The machine component receives the object and, by the actuation of the positioning elements, can be moved and positioned relative to the supporting structure. However, the machine component is intended to be movable only in the direction of the axes of a Cartesian coordinate system of the machine component, the origin of which is fixedly connected to the machine component. A tilting, pivoting or rotation of the machine component about these axes is intended to be barred. For this purpose, the known positioning device has three struts, which are attached, on the one hand, to the supporting structure and, on the other hand, to the machine component. The struts are here connected to and configured with said parts in such a way that they prevent the machine component from being pivoted about these axes. The struts have two strut portions, which are hinge-connected to each other, so that the length of the strut can be adjusted or altered by this being folded open or shut.